The present invention relates to an apparatus and method for rotating fonts, and more particularly, to an apparatus and method for rotating on-screen display (OSD) fonts.
With the rapid popularization of computer related to peripheral fields these years, many display devices, e.g. cathode ray tube (CRT) display and liquid crystal display (LCD), have been increasingly playing an important role in these fields. The performance of these display devices essentially depends on the calibration of parameters beside the optimal parameters of manufacturers, e.g. contrast, brightness, vertical and horizontal sizes, and geometric shapes etc. The on-screen display (OSD) provides users with interactive information to obtain a best display quality through the above parameters. There is a selection button for an OSD message display mode. An OSD device will receive a demand signal and be sent to central processing unit (CPU) in the OSD device to control precisely the contrast, brightness, vertical and horizontal sizes when users push the selection button inducing the demand signal. Further, the users can clearly observe the effect due to the adjustment of the parameters. Additionally, a video display is overlapped over the OSD message.
However, the conventional OSD message can""t comply with the video display when the display device is rotated, namely, the OSD message is asynchronous with the video display so that the OSD message is set in an improper position where is disadvantageous to users for viewing the parameters within the OSD message. Further, as such, it will contribute to a big deviation and inconvenient condition during adjusting the parameters. Currently, operated in line-scan to form a complete video display, most of the display devices are continuously scanned line by line in accordance with the vertical or horizontal signal of the display device. Therefore, the fonts of the OSD message must be also sequentially output into display devices. Since the vertical or horizontal signal referred to OSD device still remain invariable when the display device is rotated, the OSD message and the display device is asynchronous such that the OSD message is inconsistent with the video display resulting in improper view position for users. In FIG. 1A, after the display device is rotated, the figure shows the relation between the OSD message and the video display.
As a result, as the display device is rotated, the conventional OSD message is not able to be synchronous with the video display. Such a situation severely causes a quite inconvenience and induces a lot of errors when adjusting parameters of the display device. Moreover, the fonts of the conventional OSD message are implemented by the bit-mapped such that the processes of OSD fonts are inefficiency. Such not only consumes a lot of memory but also considerably increases computation time as rotating the OSD fonts.
In view of the foregoing, the conventional OSD device has been encountered with the problem that the OSD message is asynchronous with the video display.
As a result, the primary object of the present invention is to provide. an apparatus and method for rotating OSD fonts such that the OSD message and the video display remain in readily observable position for users.
Another object of the present invention is to provide an apparatus and method so as to greatly decrease the cost of the font read only memory (ROM) by using a font-based as a reading unit.
According to the above object, the present invention offers an apparatus and method for rotating OSD fonts. The apparatus for rotating the OSD fonts comprises an OSD rotation device including a central processing unit (CPU), font addresses generator, memory, a font ROM, a decoder, a shift register, a output controller and output circuits, a synchronization signal generator, and a display device.
In a manner, an OSD display demand is inputted into a CPU for commanding the CPU to start reading in a plurality of OSD font addresses, and a plurality of OSD fonts corresponding to the OSD font addresses are produced and stored in a memory. Next, the OSD fonts corresponding to the font addresses is read and delivered to the decoder, wherein the OSD fonts are stored initially in the font ROM. Further, the decoder performs a decoding process for the OSD fonts to form a plurality of rotated fonts. The rotated fonts are stored into storage medium and outputted sequentially into the output circuits. The OSD message, including the rotated fonts, is displayed on a display device so that the video display is synchronized with the OSD message.
In the present invention, an apparatus and method for rotating on-screen display fonts is described to remain in the preferred view between the OSD message and the video display. Further, due to the OSD fonts are read in font-based way according the present invention, the operation time of rotating the OSD fonts is much lower than that of the conventional OSD rotated fonts in bit-mapped way. Moreover, the duplicated OSD fonts can be significantly reduced in using the various rotation angles of the OSD fonts.